Varieties of battery-powered portable electronic devices are available on the market. These often include a local storage of the type of a memory capable to contain multimedia content. Such content can be loaded to the devices' storage and subsequently consumed, for instance by playing back the content.
Until now for the reason of non-volatility, flash-based memories were used. The flash-based memories however have a rather high price, as compared to for example dynamic random access memories (DRAM)-based memories. On the other hand, these DRAM-based memories are volatile, that is the data content is lost if the power supplied to memory decreases below a certain low-level threshold for instance upon consumption of power or simply shutting down the power supply.
As mentioned above, the data content is lost if the power supplied to the memory reaches a low-level threshold when decreasing. However, in order to avoid losing data content a data retention power threshold may also be used. When the power supplied to the memory first reaches this data retention data threshold, power will be economized and supplied to the DRAM-based memory to refresh the memory and hence avoid data being. In this retention state, data is not accessible to the user, rather the data is locked. If however the power supplied to the battery decreases further and reached the low-level threshold data is nevertheless lost.
Several ways to communicate the level or capacity of the battery used, exist.
In “Method for determining when a smart battery is discharged below it's critical low capacity” by Seng Pao Xiong, one way to communicate capacity to a user by using a functionality of a LED display, a host device can determine the capacity of a battery.
This way of communication thus concerns communicating information on the battery capacity as such. What the user is eager to find out is whether the battery capacity is enough to listen to a song or to watch a film before the battery runs flat. Seng Pao Xiong therefore has the disadvantage since it is not communicating information related to any available content files.